2-й метод в тестировании pythonunit не работает

Question

Я сталкиваюсь с очень странной проблемой, что модульный тест python по 2-му методу не работает.

Ниже приведен код

from selenium import webdriver
import unittest
import time


class PIM_config(unittest.TestCase):

    @classmethod
    def setUpClass(cls):
        print(" Open Application")
        cls.driver = webdriver.Chrome(executable_path='/Library/Python/2.7/site-packages/chromedriver')

        cls.driver.get("https://opensource-demo.orangehrmlive.com/")

    def test_Valid_Login(self):
        self.driver.find_element_by_id("txtUsername").send_keys("admin")
        self.driver.find_element_by_id("txtPassword").send_keys("admin123")
        self.driver.find_element_by_id("btnLogin").click()
        time.sleep(5)

    def test_PVMConfirgOption(self):
        print(" Hello")
        self.driver.find_element_by_xpath("//a[@id='welcome']").click()

    @classmethod
    def tearDownClass(self):
        print("Close Application")


    if __name__ == "__main__":
        unittest.main()

Сообщение об ошибке на консоли:

Error
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/case.py", line 59, in testPartExecutor
    yield
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/case.py", line 615, in run
    testMethod()
  File "/Users/reenupanwar/PycharmProjects/Web_Python_Automation/MatchStatus/PIM_confirg.py", line 23, in test_PVMConfirgOption
    self.driver.find_element_by_xpath("//a[@id='welcome']").click()
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 258, in find_element_by_xpath
    return self.find_element(by=By.XPATH, value=xpath)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 712, in find_element
    {'using': by, 'value': value})['value']
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/selenium/webdriver/remote/webdriver.py", line 201, in execute
    self.error_handler.check_response(response)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 181, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.NoSuchElementException: Message: no such element: Unable to locate element: {"method":"xpath","selector":"//a[@id='welcome']"}
  (Session info: chrome=73.0.3683.86)
  (Driver info: chromedriver=73.0.3683.68 (47787ec04b6e38e22703e856e101e840b65afe72),platform=Mac OS X 10.12.6 x86_64)



Assertion failed
Close Application


Ran 2 tests in 15.090s

FAILED (errors=1)

Process finished with exit code 1

Assertion failed

Assertion failed

Мой XPath на 2-х методах тестирования верен на 100%, и он работает, когда я использовал ту же строку кода в первом методе.Но при использовании второго метода я столкнулся с вышеуказанным вопросом.Пожалуйста, предложите.